The premise is that the person had evil intent and could have copied the keys.
Any guest could copy keys, you can get a key that says not be copied, not sure how guaranteed that is, but a help. How do you know which guest has evil intent and which does not?
So the reason for the claim is that you suspect the person is a crook, you have no evidence.
The keys have not been lost/stolen, I do not see how the Host Guarantee as written would apply. We know in practice it does not seem to be applied as written but this would be an expansion.
So basically you are saying I gave you a key, I think you are a crook, therefore I need to replace the lock and want you to pay for it?
I have heard of Insurance covering new locks where the keys have been lost or stolen, but not where you suspect someb ody who had access to them.
The solution is a lock that can easily be changed at no or little cost.
David